Fuel elements for several types of nuclear reactors are fabricated using cylindrical pellets or rods containing the nuclear fuel. Typical of these are the pellets or short rods to be utilized in high temperature gas cooled reactors. These typically are about 1/2 inch in diameter .times. 3 inch in length and may be prepared using equipment based on the technology described in U.S. Pat. No. 3,763,292. Each pellet or rod must be of uniform diameter and substantially free from surface imperfections to ensure adequate heat transfer to any surrounding cladding during operation.
The fabrication of fuel pellets or rods, particularly using recycle nuclear fuel, will be performed in shielded facilities and thus any inspection device must be remotely operated. One inspection device that has been utilized in the past has been an optical comparative system as used by the Gulf Atomic Company. A major disadvantage of that system is the high cost of the equipment.
A need exists to provide an accurate, in-line, automatic, remotely-operated inspection system of reduced cost. The present invention was conceived to meet this need in a manner to be described hereinbelow.